open-consul/agent/service_manager.go

544 lines
16 KiB
Go

package agent
import (
"fmt"
"sync"
"github.com/hashicorp/consul/agent/cache"
cachetype "github.com/hashicorp/consul/agent/cache-types"
"github.com/hashicorp/consul/agent/structs"
"github.com/imdario/mergo"
"github.com/mitchellh/copystructure"
"golang.org/x/net/context"
)
// The ServiceManager is a layer for service registration in between the agent
// and the local state. Any services must be registered with the ServiceManager,
// which then maintains a long-running watch of any globally-set service or proxy
// configuration that applies to the service in order to register the final, merged
// service configuration locally in the agent state.
type ServiceManager struct {
agent *Agent
// servicesLock guards the services map, but not the watches contained
// therein
servicesLock sync.Mutex
// services tracks all active watches for registered services
services map[structs.ServiceID]*serviceConfigWatch
// registerCh is a channel for processing service registrations in the
// background when watches are notified of changes. All sends and receives
// must also obey the ctx.Done() channel to avoid a deadlock during
// shutdown.
registerCh chan *asyncRegisterRequest
// ctx is the shared context for all goroutines launched
ctx context.Context
// cancel can be used to stop all goroutines launched
cancel context.CancelFunc
// running keeps track of live goroutines (worker and watcher)
running sync.WaitGroup
}
func NewServiceManager(agent *Agent) *ServiceManager {
ctx, cancel := context.WithCancel(context.Background())
return &ServiceManager{
agent: agent,
services: make(map[structs.ServiceID]*serviceConfigWatch),
registerCh: make(chan *asyncRegisterRequest), // must be unbuffered
ctx: ctx,
cancel: cancel,
}
}
// Stop forces all background goroutines to terminate and blocks until they complete.
//
// NOTE: the caller must NOT hold the Agent.stateLock!
func (s *ServiceManager) Stop() {
s.cancel()
s.running.Wait()
}
// Start starts a background worker goroutine that writes back into the Agent
// state. This only exists to keep the need to lock the agent state lock out of
// the main AddService/RemoveService codepaths to avoid deadlocks.
func (s *ServiceManager) Start() {
s.running.Add(1)
go func() {
defer s.running.Done()
for {
select {
case <-s.ctx.Done():
return
case req := <-s.registerCh:
req.Reply <- s.registerOnce(req.Args)
}
}
}()
}
// runOnce will process a single registration request
func (s *ServiceManager) registerOnce(args *addServiceRequest) error {
s.agent.stateLock.Lock()
defer s.agent.stateLock.Unlock()
err := s.agent.addServiceInternal(args)
if err != nil {
return fmt.Errorf("error updating service registration: %v", err)
}
return nil
}
// AddService will (re)create a serviceConfigWatch on the given service. For
// each call of this function the first registration will happen inline and
// will read the merged global defaults for the service through the agent cache
// (regardless of whether or not the service was already registered). This
// lets validation or authorization related errors bubble back up to the
// caller's RPC inline with their request. Upon success a goroutine will keep
// this updated in the background.
//
// If waitForCentralConfig=true is used, the initial registration blocks on
// fetching the merged global config through the cache. If false, no such RPC
// occurs and only the previousDefaults are used.
//
// persistServiceConfig controls if the INITIAL registration will result in
// persisting the service config to disk again. All background updates will
// always persist.
//
// service, chkTypes, persist, token, replaceExistingChecks, and source are
// basically pass-through arguments to Agent.addServiceInternal that follow the
// semantics there. The one key difference is that the service provided will be
// merged with the global defaults before registration.
//
// NOTE: the caller must hold the Agent.stateLock!
func (s *ServiceManager) AddService(req *addServiceRequest) error {
req.fixupForAddServiceLocked()
req.service.EnterpriseMeta.Normalize()
// For now only sidecar proxies have anything that can be configured
// centrally. So bypass the whole manager for regular services.
if !req.service.IsSidecarProxy() && !req.service.IsMeshGateway() {
// previousDefaults are ignored here because they are only relevant for central config.
req.persistService = nil
req.persistDefaults = nil
req.persistServiceConfig = false
return s.agent.addServiceInternal(req)
}
var (
service = req.service
chkTypes = req.chkTypes
previousDefaults = req.previousDefaults
waitForCentralConfig = req.waitForCentralConfig
persist = req.persist
persistServiceConfig = req.persistServiceConfig
token = req.token
replaceExistingChecks = req.replaceExistingChecks
source = req.source
)
reg := &serviceRegistration{
service: service,
chkTypes: chkTypes,
persist: persist,
token: token,
replaceExistingChecks: replaceExistingChecks,
source: source,
}
s.servicesLock.Lock()
defer s.servicesLock.Unlock()
sid := service.CompoundServiceID()
// If a service watch already exists, shut it down and replace it.
oldWatch, updating := s.services[sid]
if updating {
oldWatch.Stop()
delete(s.services, sid)
}
// Get the existing global config and do the initial registration with the
// merged config.
watch := &serviceConfigWatch{
registration: reg,
updateCh: make(chan cache.UpdateEvent, 1),
agent: s.agent,
registerCh: s.registerCh,
}
err := watch.RegisterAndStart(
previousDefaults,
waitForCentralConfig,
persistServiceConfig,
s.ctx,
&s.running,
)
if err != nil {
return err
}
s.services[sid] = watch
if updating {
s.agent.logger.Debug("updated local registration for service", "service", service.ID)
} else {
s.agent.logger.Debug("added local registration for service", "service", service.ID)
}
return nil
}
// NOTE: the caller must hold the Agent.stateLock!
func (s *ServiceManager) RemoveService(serviceID structs.ServiceID) {
s.servicesLock.Lock()
defer s.servicesLock.Unlock()
if oldWatch, exists := s.services[serviceID]; exists {
oldWatch.Stop()
delete(s.services, serviceID)
}
}
// serviceRegistration represents a locally registered service.
type serviceRegistration struct {
service *structs.NodeService
chkTypes []*structs.CheckType
persist bool
token string
replaceExistingChecks bool
source configSource
}
// serviceConfigWatch is a long running helper for composing the end config
// for a given service from both the local registration and the global
// service/proxy defaults.
type serviceConfigWatch struct {
registration *serviceRegistration
defaults *structs.ServiceConfigResponse
agent *Agent
registerCh chan<- *asyncRegisterRequest
// cacheKey stores the key of the current request, when registration changes
// we check to see if a new cache watch is needed.
cacheKey string
// updateCh receives changes from cache watchers
updateCh chan cache.UpdateEvent
ctx context.Context
cancelFunc func()
running sync.WaitGroup
}
// NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) RegisterAndStart(
previousDefaults *structs.ServiceConfigResponse,
waitForCentralConfig bool,
persistServiceConfig bool,
ctx context.Context,
wg *sync.WaitGroup,
) error {
service := w.registration.service
// Either we explicitly block waiting for defaults before registering,
// or we feed it some seed data (or NO data) and bypass the blocking
// operation. Either way the watcher will end up with something flagged
// as defaults even if they don't actually reflect actual defaults.
if waitForCentralConfig {
if err := w.fetchDefaults(); err != nil {
return fmt.Errorf("could not retrieve initial service_defaults config for service %q: %v", service.ID, err)
}
} else {
w.defaults = previousDefaults
}
// Merge the local registration with the central defaults and update this service
// in the local state.
merged, err := w.mergeServiceConfig()
if err != nil {
return err
}
// The first time we do this interactively, we need to know if it
// failed for validation reasons which we only get back from the
// initial underlying add service call.
err = w.agent.addServiceInternal(&addServiceRequest{
service: merged,
chkTypes: w.registration.chkTypes,
persistService: w.registration.service,
persistDefaults: w.defaults,
persist: w.registration.persist,
persistServiceConfig: persistServiceConfig,
token: w.registration.token,
replaceExistingChecks: w.registration.replaceExistingChecks,
source: w.registration.source,
})
if err != nil {
return fmt.Errorf("error updating service registration: %v", err)
}
// Start the config watch, which starts a blocking query for the
// resolved service config in the background.
return w.start(ctx, wg)
}
// NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) fetchDefaults() error {
req := makeConfigRequest(w.agent, w.registration)
raw, _, err := w.agent.cache.Get(cachetype.ResolvedServiceConfigName, req)
if err != nil {
return err
}
reply, ok := raw.(*structs.ServiceConfigResponse)
if !ok {
// This should never happen, but we want to protect against panics
return fmt.Errorf("internal error: response type not correct")
}
w.defaults = reply
return nil
}
// Start starts the config watch and a goroutine to handle updates over the
// updateCh. This is safe to call more than once assuming you have called Stop
// after each Start.
//
// NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) start(ctx context.Context, wg *sync.WaitGroup) error {
w.ctx, w.cancelFunc = context.WithCancel(ctx)
// Configure and start a cache.Notify goroutine to run a continuous
// blocking query on the resolved service config for this service.
req := makeConfigRequest(w.agent, w.registration)
w.cacheKey = req.CacheInfo().Key
// We use the cache key as the correlationID here. Notify in general will not
// respond on the updateCh after the context is cancelled however there could
// possible be a race where it has only just got an update and checked the
// context before we cancel and so might still deliver the old event. Using
// the cacheKey allows us to ignore updates from the old cache watch and makes
// even this rare edge case safe.
err := w.agent.cache.Notify(
w.ctx,
cachetype.ResolvedServiceConfigName,
req,
w.cacheKey,
w.updateCh,
)
if err != nil {
w.cancelFunc()
return err
}
w.running.Add(1)
wg.Add(1)
go w.runWatch(wg)
return nil
}
func (w *serviceConfigWatch) Stop() {
w.cancelFunc()
w.running.Wait()
}
// runWatch handles any update events from the cache.Notify until the
// config watch is shut down.
//
// NOTE: the caller must NOT hold the Agent.stateLock!
func (w *serviceConfigWatch) runWatch(wg *sync.WaitGroup) {
defer wg.Done()
defer w.running.Done()
for {
select {
case <-w.ctx.Done():
return
case event := <-w.updateCh:
if err := w.handleUpdate(event); err != nil {
w.agent.logger.Error("error handling service update", "error", err)
}
}
}
}
// handleUpdate receives an update event the global config defaults, updates
// the local state and re-registers the service with the newly merged config.
//
// NOTE: the caller must NOT hold the Agent.stateLock!
func (w *serviceConfigWatch) handleUpdate(event cache.UpdateEvent) error {
// If we got an error, log a warning if this is the first update; otherwise return the error.
// We want the initial update to cause a service registration no matter what.
if event.Err != nil {
return fmt.Errorf("error watching service config: %v", event.Err)
}
res, ok := event.Result.(*structs.ServiceConfigResponse)
if !ok {
return fmt.Errorf("unknown update event type: %T", event)
}
// Sanity check this even came from the currently active watch to ignore
// rare races when switching cache keys
if event.CorrelationID != w.cacheKey {
// It's a no-op. The new watcher will deliver (or may have already
// delivered) the correct config so just ignore this old message.
return nil
}
w.defaults = res
// Merge the local registration with the central defaults and update this service
// in the local state.
merged, err := w.mergeServiceConfig()
if err != nil {
return err
}
// While we were waiting on the agent state lock we may have been shutdown.
// So avoid doing a registration in that case.
select {
case <-w.ctx.Done():
return nil
default:
}
registerReq := &asyncRegisterRequest{
Args: &addServiceRequest{
service: merged,
chkTypes: w.registration.chkTypes,
persistService: w.registration.service,
persistDefaults: w.defaults,
persist: w.registration.persist,
persistServiceConfig: true,
token: w.registration.token,
replaceExistingChecks: w.registration.replaceExistingChecks,
source: w.registration.source,
},
Reply: make(chan error, 1),
}
select {
case <-w.ctx.Done():
return nil
case w.registerCh <- registerReq:
}
select {
case <-w.ctx.Done():
return nil
case err := <-registerReq.Reply:
if err != nil {
return fmt.Errorf("error updating service registration: %v", err)
}
return nil
}
}
type asyncRegisterRequest struct {
Args *addServiceRequest
Reply chan error
}
func makeConfigRequest(agent *Agent, registration *serviceRegistration) *structs.ServiceConfigRequest {
ns := registration.service
name := ns.Service
var upstreams []structs.ServiceID
// Note that only sidecar proxies should even make it here for now although
// later that will change to add the condition.
if ns.IsSidecarProxy() {
// This is a sidecar proxy, ignore the proxy service's config since we are
// managed by the target service config.
name = ns.Proxy.DestinationServiceName
// Also if we have any upstreams defined, add them to the request so we can
// learn about their configs.
for _, us := range ns.Proxy.Upstreams {
if us.DestinationType == "" || us.DestinationType == structs.UpstreamDestTypeService {
sid := us.DestinationID()
sid.EnterpriseMeta.Merge(&ns.EnterpriseMeta)
upstreams = append(upstreams, sid)
}
}
}
req := &structs.ServiceConfigRequest{
Name: name,
Datacenter: agent.config.Datacenter,
QueryOptions: structs.QueryOptions{Token: agent.tokens.AgentToken()},
UpstreamIDs: upstreams,
EnterpriseMeta: ns.EnterpriseMeta,
}
if registration.token != "" {
req.QueryOptions.Token = registration.token
}
return req
}
// mergeServiceConfig returns the final effective config for the watched service,
// including the latest known global defaults from the servers.
//
// NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) mergeServiceConfig() (*structs.NodeService, error) {
if w.defaults == nil {
return w.registration.service, nil
}
// We don't want to change s.registration in place since it is our source of
// truth about what was actually registered before defaults applied. So copy
// it first.
nsRaw, err := copystructure.Copy(w.registration.service)
if err != nil {
return nil, err
}
// Merge proxy defaults
ns := nsRaw.(*structs.NodeService)
if err := mergo.Merge(&ns.Proxy.Config, w.defaults.ProxyConfig); err != nil {
return nil, err
}
if err := mergo.Merge(&ns.Proxy.Expose, w.defaults.Expose); err != nil {
return nil, err
}
if ns.Proxy.MeshGateway.Mode == structs.MeshGatewayModeDefault {
ns.Proxy.MeshGateway.Mode = w.defaults.MeshGateway.Mode
}
// Merge upstream defaults if there were any returned
for i := range ns.Proxy.Upstreams {
// Get a pointer not a value copy of the upstream struct
us := &ns.Proxy.Upstreams[i]
if us.DestinationType != "" && us.DestinationType != structs.UpstreamDestTypeService {
continue
}
// default the upstreams gateway mode if it didn't specify one
if us.MeshGateway.Mode == structs.MeshGatewayModeDefault {
us.MeshGateway.Mode = ns.Proxy.MeshGateway.Mode
}
usCfg, ok := w.defaults.UpstreamIDConfigs.GetUpstreamConfig(us.DestinationID())
if !ok {
// No config defaults to merge
continue
}
if err := mergo.Merge(&us.Config, usCfg); err != nil {
return nil, err
}
}
return ns, err
}